CHAPTER 5. DIAGNOSING CONCUSSION
concussion, as well as in the
following weeks and months.
Specifically, she has been
examining brain networks,
which are the different
patterns of activity associated
with different brain functions.
There are networks in the
brain that are engaged
during different activities, for
example, during movement
or emotional responses.
The symptoms in diseases
such as Alzheimer’s and
schizophrenia result from
disruption to these networks.
For concussion, research
is showing a similar brain
network disruption, but
one network in particular is
affected. It’s known as the
‘default mode’ network and
it’s the one that’s most active
when our brain is in what
could be called ‘idling mode’.
We don’t yet understand why
this network is so important,
or why it is particularly badly
affected by concussion. But,
says Dr Nasrallah, changes
to this network are apparent
soon after concussion.
For her work on brain
networks she’s been using
laboratory mice, which
provide good clues to what’s
going on in our brains because
like us they’re mammals.
Dr Nasrallah has also been
gathering information about
what happens inside the
heads of military personnel
exposed to blast injuries, when
they’re not close enough to
be knocked over but close
enough to feel shock waves,
which may shake the brain
about inside the skull.
PET
Positron emission tomography
(PET) is a form of imaging
that uses a radioactive
tracer to highlight certain
types of material in the
brain. For concussion, it’s
being used to study the
development of abnormal
tau tangles. These are known
to be a feature of chronic
traumatic encephalopathy
(CTE), which is a form of
dementia associated with
repeated concussions .
A US study of former NFL
players suspected of having
CTE used PET to generate
maps of how tau tangles
were distributed through the
brain. Firstly, these tangles
were confirmed to be absent
from the brains of people
who hadn’t played football. In
the ex-footballers the tangles
were present and appeared
to follow a particular pattern
of formation. They appeared
THE MESSAGE
Brain imaging studies are helping us understand what
is going on in the brain during concussion. It’s also
hoped they might show characteristic changes with
concussion or CTE that can be used to diagnose these
conditions and monitor recovery. The reality is that what
researchers are likely to find are a series of indicators
that can be used by doctors in combination with clinical
assessments to make a diagnosis of concussion and
assess the recovery time required. That will enable
doctors to predict who is more likely to suffer long-
term consequences from concussion and allow them to
intervene early to prevent or limit the damage.
first in the midbrain region,
then moved to subcortical
areas and the part of the
brain that controls anxiety
and stress, and finally showed
up in the cortex. This was in
contrast to what is seen in
Alzheimer’s patients, where
tau tangles appear first in
two areas: the hippocampus
and the entorhinal cortex,
which are both important in
memory and navigation.